Might consider interval type training. Takes less time invested and gives pretty quick results. Don't need 20, 60 or more minutes to gain prime results. Short burst of 20 seconds, followed by a 10 seconds pause...than 20 seconds- pause 10 seconds, etc, etc.. Cycle this method from 5 to 8 times a workout. Try a search to get more information and different choices of exercises. Can use a spin bike (excellent), row machine, punching bag, etc.
Many versions of interval training, which can include other forms of workouts/exercises than only running. Tabata is an example of workouts that fit the above suggestions very well. If you want to run, that try 20 second sprints, followed by 10 seconds of rest, etc.....5 to 8 cycles. Not only burn fat, improve stamina (endurance+ strength) but the calves can take on a new and improved look.
Try doing interval on off training days, only take a few minutes for max results. If you just want to do regular running, try not running after a serious weight workout....wait a couple hours at lease. Want to keep the blood (which include important amino acids, hormones, etc for rebuilding muscle mass) in the muscle area work for a while. You worked hard for that pump, try keeping it as long as you can for muscle building purposes.
Good Luck.